#include <stdio.h>
#include <stdlib.h>

int mystrlen(char* src)
{
    if(src == NULL) {
        return 0;
    }
    int count = 0;
    char* len = src;
    while(*len++ != '\0') {
        ++count;
    }
    return count;
}

int main()
{
    char *src = "Hello World!!\n";
    int len = mystrlen(src);
    printf("%d\n", len);
    return 0;
}
